At first, it started as a half loco, then I just thought it would make a great bookend.

About this creation

But why did I build the half of a loco? Well, because there is a half loco like that. In 1999, locomotive M61 004 of MÁV (Hungarian State Railways) hit a tree fallen on the tracks. The crash damaged it beyond repair, but one end of its body was restored and placed at the Transport Museum of Budapest.
The NoHAB is a very tricky build with its curves, so I used other LEGO NoHABs for inspiration. The hardest part ("was lettin' go not taking part", sorry, reminded me of a Coldplay song) was the sad-looking windows. I think I got a quite nice solution for that, and the overall shape turned out well enough.
The loco M61 004 at the Transport Museum of Budapest.